1.
a = eval(input('请输入年份：'))
if a %4==0 and a %100!=0 or a %400==0:
    print('是闰年')
else:
    print('不是闰年')

2.
i = 1
while i <=100:
    if 70 <= i < 80:
        i += 1
        continue
    if i % 13 == 0:
        print(i)
    i += 1

3.
n = int(input('请输入行数:'))
for i in range(n, 0, -1):
    print(" " * (n - i) + "*" * (2 * i - 1))